An analog to digital converter circuit is used in a vehicle for converting a sensor output indicating a remaining fuel level in a tank to digital data. The converter circuit also controls a pointer instrument or a display device based on the digital data for displaying the fuel level. When the converter circuit is formed on a printed circuit board (PCB) having a jumper printed on its surface, the digital data includes a detection error associated with the jumper. Such a PCB is proposed in U.S. Pat. No. 5,466,893 (JP-B-2763951) and shown in FIG. 5.
The PCB includes a substrate 51 and a copper paste jumper 53 printed on the substrate 51. The jumper 53 is silk-printed in the form of a thin plate for electrically connecting a first land 52a with a second land 52b. The jumper 53 and the lands 52a and 52b are covered by an over coat 54 and an under coat 55 that are made of electrical insulating material.
In a silk-printing process of the jumper 53, a printed area of the jumper 53 varies between substrates. As a result, resistance of the jumper 53 varies between substrates. The variations in the resistance result in the detection error and low accuracy in the digital data conversion.